Recap - Alkanes

The first homologous series is the alkanes. Their names all end in –ane.

The alkanes have many uses:

  • methane – (natural gas) cooking, heating
  • propane – used in gas cylinders for BBQ etc
  • octane – used in petrol for cars

The general formula of the alkanes is {C_n}{H_{2n + 2}}. They are insoluble in water.

The first four alkanes. Methane (CH4) is a carbon atom bonded to four individual hydrogen atoms. Ethane (C2H6) has two carbons bonded to each other. The remaining three bonds on each carbon connect to a single hydrogen. Propane (C3H8) has a carbon with three hydrogens joined to a carbon with two hydrogens joined to a carbon with three hydrogens (CH3CH2CH3). Butane (C4H10) has a carbon with three hydrogens joined to a carbon with two hydrogens joined to a carbon with two hydrogens joined to a carbon with three hydrogens (CH3CH2CH2CH3).

The names, molecular formula and the structural formula of the first eight alkanes must be learned. Using a mnemonic can make learning the names easier.

MethaneCH4Monsters
EthaneC2H6Eat
PropaneC3H8Pupils
ButaneC4H10But
PentaneC5H12Prefer
HexaneC6H14Hairy
HeptaneC7H16Haggis
OctaneC8H18Occasionally

General formula, functional group and properties of alkanes.